The present invention relates to a measuring device, in particular a hand-held device for measuring distances.
In order to attain the most accurate measurement result possible when performing a measurement, e.g., a distance measurement, it is advantageous when a known reference variable, e.g., a known reference distance in the case of a distance measurement, is available. With the aid of a reference variable of this type, the measurement device may be, e.g., calibrated occasionally, or transit times of the measurement signal inside the device may be determined so that they may be taken into account in a measurement.
Publication DE 198 040 50 A1 makes known a distance measurement with a laser diode and a photodiode for generating and/or receiving a send or receive signal. In order to calibrate this distance-measuring device, it is provided with an adjustable flap, which, when a reference measurement is carried out, is swiveled by a servo drive into an optical path of the transmitted measurement signal, thereby deflecting the transmitted measurement signal and directing it via a reference path directly to the photodiode.
Publication EP 1351070 A1 makes known an electro-optical, para-axial distance-measuring system, with which a rigid, stationary edge extends into the transmission path of the measuring device, in order to direct a portion of the measurement beam directly onto the receiving diode or an additional reference diode.
Publication DE 43 163 48 A1 makes known a device for measuring distance, which includes a switchable beam-deflection device, which may be swiveled about an axis using a motor. The surface of the beam-deflection device struck by the measurement beam reflects a directed, divergent light cone in the direction of an optical fiber, which is used as an optical waveguide. The opening of the light cone is so great that radiation may penetrate the incident face of the optical waveguide in all positions of the laterally displaceable optical waveguide.